How do I make the supports for the roof of the car?
Edit mode, use circle-select C to highlight these corner vertices of the hood.  

  

Turn on Proportional-editing with the little blue-dot icon at the bottom of your screen.  E Extract, then use G Grab, R Rotate, and S Scale down a little.  

Use X Y and Z constraints where needed.  

Repeat this a few times to extend your vertices in the right direction, and get the level of detail you're going for.  The more times you extrude, the more control-points you'll end up with.    

It may be easier to bring down a secondary view-screen by dragging down on the \\ diagonal-slashes in the corner of your viewport.  Set one to front-view, and the other to side, with your numpad.  

I'd also recommend naming your objects in the heirarchy-tree, so it's easier to tell what items are what.